pathyvr6 Posted February 28, 2010 Share Posted February 28, 2010 i need some help on how to change my crank sensor on my 87 pathfinder i was able to locat it but im not sure how to change it out if anyone has done one before or knows how to do it please let me know im new into pathfinders so some of this stuff is new to me. thanks Link to comment Share on other sites More sharing options...
GrimGreg Posted March 1, 2010 Share Posted March 1, 2010 I'm pretty sure you need to pull the distributor to do the swap. Link to comment Share on other sites More sharing options...
PATHRIDER Posted March 1, 2010 Share Posted March 1, 2010 isnt it inside the dizzy cup? Link to comment Share on other sites More sharing options...
pathyvr6 Posted March 1, 2010 Author Share Posted March 1, 2010 from reading on google its telling me its on top of the transmission bell housing so i looked and sure enough there it is but now i have no idea how to take it out there isnt any bolts i can see around it the could be holding it on there theres just 2 wires comeing out of it going to a connector which i disconnected hoping i could twist it and pull it out or something but i was wrong got any ideas Link to comment Share on other sites More sharing options...
Precise1 Posted March 2, 2010 Share Posted March 2, 2010 What year? Have you looked in the down loadable Factory Service Manual (only for MPFI 1990+) pinned in the Garage Section? B Link to comment Share on other sites More sharing options...
pathyvr6 Posted March 2, 2010 Author Share Posted March 2, 2010 it an 87 sorry i completely forgot to put that it would prebly help out a lot lol its got a VG30i engine with auto tranny Link to comment Share on other sites More sharing options...
RedPath88 Posted March 2, 2010 Share Posted March 2, 2010 The CAS (Crank Angle Sensor, also called a Crank Position Sensor) is located inside the dizzy on all petro burning WD21's. It can be replaced separately but from what I know (and have always been told) it is such a sensitive part (dust, moisture, etc) that replacing the complete dizzy is often recommended. Depending on what brand and where your buying from, a complete distributor may only be a little more than just the CAS. Link to comment Share on other sites More sharing options...
PATHRIDER Posted March 2, 2010 Share Posted March 2, 2010 The CAS (Crank Angle Sensor also called a Crank Position Sensor) is located inside the dizzy on all petro burning WD21's. It can be replaced separately but from what I know (have always been told) it is such a sensitive part (dust, moisture, etc) that replacing the complete dizzy is often recommended. Depending on what brand and where your buying from, a complete distributor may only be a little more than just the CAS. arghhh...I just replaced my dizzy yesterday but from trying to remove the old rotor that seized I squirt it with a bit of pb blaster and it sipped inside the sensor ( under the gold cap..I opened it up and theres a bit of pb on there so I sprayed it with electonis cleaner and used a air gun to dry it.. Do you think that damaged my distributor? Link to comment Share on other sites More sharing options...
PATHRIDER Posted March 2, 2010 Share Posted March 2, 2010 A. The most common cause of this symptom is a bad Crankshaft Position Sensor (CPS) inside the distributor. PURPOSE: The Crankshaft Position sensor, located in the distributor, monitors engine speed and piston position. OPERATION: When the rotor passes between the photo diodes and Light Emitting Diodes (LED) the slits in the rotor plate cut the light being transmitted to the photo diode from the LED. This generates rough-shaped pulses which are changed into ON/OFF signals by the wave forming circuit. The Engine Control Module (ECM) interprets these signals to calculate engine rpm and cylinder position. Nissan Altima Dies, Won't Restart When Hot Crankshaft Position Sensor CONSTRUCTION: The unit has a rotor plate and a wave forming circuit. The rotor plate has 360 slits for 1° signals and 4 slits for 180° signals. Photo diodes and light emitting diodes (LED's) are used for the wave forming circuit. If there is oil in the distributor coming up past the shaft seal, then it is possible the oil may be filling in some of the slits and causing the engine to die. However, it is much more likely the CPS itself is bad. Sometimes you can confirm this by letting the engine run for about 30 to 45 minutes with the hood closed, then tapping the side of the distributor with a small hammer. If the engine dies, you have a bad CPS for sure. If it doesn't, the next time you drive it and it dies, check for spark at once. If there is no spark then you probably do have a bad CPS. The problem is if you check it when the engine is running normally, it will check out as good. Link to comment Share on other sites More sharing options...
RedPath88 Posted March 2, 2010 Share Posted March 2, 2010 Only thing you can do is try it. Unless I am thinking of another, Nissan's CAS uses an optical sensor and a slotted rotor/disk for it's readings. I have never taken a Nissan CAS apart, but did have the cap off years ago (when I had a suspected bad dizzy and/or CAS) and iirc you can see the "eye" and the slotted disk if you take it all apart. Contaminates such as dust can cause misreadings. You could try cleaning it better, I don't know what effect electronics cleaner might have on the assembly, I would think that it would be ok. But it could cause a haze on the eye which would mess with the readings. Maybe we can get 5523Pathfinder in this thread and see what input he can provide... in fact, I will PM him Link to comment Share on other sites More sharing options...
RedPath88 Posted March 2, 2010 Share Posted March 2, 2010 Yep, that is the one I was thinking of Link to comment Share on other sites More sharing options...
PATHRIDER Posted March 2, 2010 Share Posted March 2, 2010 im going to try and fire it up tomorrow morning and hope for the best Link to comment Share on other sites More sharing options...
pathyvr6 Posted March 2, 2010 Author Share Posted March 2, 2010 man things with these pathfinders r more compltecated then i thought i dont even know if its the crank sensor anymore from reading other threads and replies with my 87 pathy i had just finished canging the break calipers on both sides so i wanted to take it out and test them after i was finished the pathy had been sitting in my garage for a few days so it was cold i started it and backed it out of the garage and let it warm up for about 10 mines i drove it about 2 block then turned, after i turned i tryed speeding back up again but every time i put my foot on the gas it would bog down and give me no power, unless i held the pedal down for about 15 seconds then the rpms would jump up enough for me to move, i had to nurse it back about 2 block like this to my house. i managed to get it back into the garage. i turned it off when i got into the garage and since then it hasnt wanted to start i have checked the coil, plugs, wires, and the distributor, the distributor is pushing out power but im not sure if its enough. anyone got any ideas im fresh out now Link to comment Share on other sites More sharing options...
pathyvr6 Posted March 2, 2010 Author Share Posted March 2, 2010 im going to try and fire it up tomorrow morning and hope for the best good luck with urs Link to comment Share on other sites More sharing options...
RedPath88 Posted March 2, 2010 Share Posted March 2, 2010 Start with this: Ecu Self-diagnostics For 87-95 Pathfinder Link to comment Share on other sites More sharing options...
5523Pathfinder Posted March 2, 2010 Share Posted March 2, 2010 The bearing in the distributor has been known to wear, causing the driveshaft to "wobble" in the housing. This causes the housing to wear and "shavings" float around the distributor. These shavings can get into everything, including the optical ring for the cam position sensor. This can cause hard and no starts. Basicly, the ECM does not know where the engine is as far as timing. This actually happened to my Pathfinder. I found it while trying to diagnois another problem. I replaced the distributor as a whole, and everything has been fine. Any play in the distributor is bad. Sounds like you have a ignition or fuel problem. What color is the spark? If its yellow to orange, you have weak spark. It should be blue to almost white. You may have another problem in the injectors. I have replaced many because the injectors fail mechanically. This will not throw a malfunction code. If you have access to a FSM, disconnect one injector at a time and see if it will run. IIRC, they both should operate when starting, the it will cut to one. The other injector kicks in under load. See if any codes are present and post them up. Link to comment Share on other sites More sharing options...
JamesRich Posted March 3, 2010 Share Posted March 3, 2010 You may have another problem in the injectors. I have replaced many because the injectors fail mechanically. This will not throw a malfunction code. If you have access to a FSM, disconnect one injector at a time and see if it will run. IIRC, they both should operate when starting, the it will cut to one. The other injector kicks in under load. See if any codes are present and post them up. so if the "other" injector isn't working will it throw a code or just run weak? I didn't do the self diagnosis but used my old snap-on scanner to check my ECM when I first got the truck and it was clear. My truck runs smooth just has no power. If I give it a little throttle or floor it there is no difference in acceleration. I haven't had a chance to really go through it but there is nothing obvious wrong. I will have to look at them with my timing light to see if they both spray. Will just revving it hard in neutral make the other injector spray? James Link to comment Share on other sites More sharing options...
5523Pathfinder Posted March 3, 2010 Share Posted March 3, 2010 (edited) As far as I remember, just revving it will not operate the other injector. Thats why we do the unplug test. They ar both supposed to squirt to start and idle for a certian time. Basicly, if it wont start with one unplugged, you got a stuck injector. You can take them out and have them tested in some areas. We had a place called Dr. Injector back in the day. Not too sure if they are around anymore, but there has to be others. Like I stated, if they have a mechanical failure, the ecm thinks all is ok, and wont throw a code. Edited March 3, 2010 by 5523Pathfinder Link to comment Share on other sites More sharing options...
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